/*
    This file is part of the substandard lisp implementation of Standard Lisp
    Copyright (C) 2011 Nicky Nickell

    substandard lisp is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

(de assoc (u v)
  (cond
    ((null v) NIL)
    ((atom (car v)) (error 0 (list v "is a poorly formed alist")))
    ((equal u (caar v)) (car v))
    (T (assoc u (cdr v)))))

/*---
name: assoc

doc: |
  explaining what assoc is / how it is used!

tests: |
  (setq l (pair '(a b c) '(1 2 3))) -> ((a . 1) (b . 2) (c . 3))
  (assoc 'a l) -> (a . 1)
  (assoc 'b l) -> (b . 2)
  (assoc 'c l) -> (c . 3)
  (assoc 'd l) -> NIL
...*/
